1. Field of Invention
The invention relates to the field of electrical firing mechanisms for miniature bombs, mines, missiles, and projectiles, and particularly to a device for firing a primer of the type having, in particular, an electrical power supply for a circuit including in particular, a switch, an ignition device for igniting the primer, such as an electrical resistor, or a striker and an actuation device to actuate the striker.
2. Description of Related Art
A certain number of devices for firing a primer are already known. Patent Application No. FR2742859, for example, describes a time-settable priming device including a primer, an electrical power supply for a circuit, including principally a priming resistor, a switch for switching the supply circuit of the priming resistor, a timer for setting a time delay, and a control switch for controlling switching, including a microcontroller, a code wheel, and a trapping device connected to the microcontroller.
As an example, the trapping device can be of the contact-opening type and includes a closed circuit supplied by a supply device. The trapping device may have a certain number of contacts opened by remote control, inertia, or a tripwire.
These types of contacts may have drawbacks when implemented in an antitank land mine. In certain cases, it is not possible to provide remote-controlled or inertial tripping and moreover, the tripwire does not discriminate between a soldier and a vehicle when firing the primer.
To overcome this problem and to actuate firing only in the presence of a vehicle, Patent FR2653824 states that, for recognition of a vehicle, use may be made, for example, of a detector sensitive to contact by the vehicle or to pressure, a detector sensitive to the vehicle""s magnetic field, or to the change in the magnetic field of the ground caused by the vehicle, or a vibration detector. The use of double detection with an influence detector and a contact or pressure detector is also described.
Detectors sensitive to contact with, or the pressure of, a vehicle include those described in patents FR2504254 and FR2507307. FR2504254 describes an antitank mine, including a detector at its upper part that includes, in particular, a pressure plate designed to actuate firing by igniting a pyrotechnic chain composed of a striker, a primer, an ignition relay, and an ignition block for firing the true pyrotechnic charge contained in the mine.
FR2507307 describes an antitank mine having a release charge and a true charge as well as double detection of the tank with a detector for firing the release charge followed by the true charge, and a contact or pressure detector causing direct firing of the true charge.
All the devices described in the aforesaid patents have drawbacks. Thus, the plate mine described in patent FR2504254 requires the vehicle to be destroyed to pass right over the mine, which considerably reduces the probability that the mine will act on the vehicle.
Patents FR2654824 and FR2507307 teach the possibility of considerably increasing the range of a mine by using influence detection in addition to contact or pressure detection.
However, this double detection requires the presence of two separate electronic assemblies, thus, increasing the number of components and hence the cost of the primer firing device, and reducing the overall reliability of the device.
Moreover, the devices described in these latter patents do not optimize the effects of the mine explosion on the tank.
The invention provides a firing device for firing a primer, requiring a minimum of electronic components and, although using only one type of detector having a greater range than that of a device as described in Patent FR2504254, for example, enabling the effects of the explosive device associated with the firing device to be optimized.
The firing device may include at least one electrical power supply, a detector, a switch, and an ignition device, such as an electrical resistor, or a striker and device able to move the striker and ignite the primer. The detector and switch may include a network of contacts able to open or close a circuit including at least the electrical power supply, under the influence of a contact or a force, to close or open the circuit when the contact or the force disappears.
According to one particular feature, the network includes of a strip of contacts. According to another feature, the contacts include membrane switches.
According to another feature, the membrane switches include a first plate having a hole, a second plate itself having a hole, and sloping edges inscribed in the hole in the first plate, a spherical membrane shaped like an upwardly directed spherical segment attached to the ends of the sloping edges, and an electrically conducting strip attached to the lower surface of the membrane.
According to one preferred feature for introducing a detection threshold, specifically a pressure threshold, the network is disposed inside a deformable sheath made of a material whose hardness is preferably greater than 40xc2x0 Shore. The choice of the shape of the sheath, the material or materials of which it is made, and the composition of the membrane switches, allows introduction of a minimum pressure threshold above which the membrane switch can close and below which it cannot do so.
According to one particular feature, this sheath is made of an extruded silicone shape whose hardness can be 60xc2x0 Shore. According to one preferred feature, the sheath has several segments delimited by a change in its structure in order to facilitate its bending. According to an additional feature, this change in structure of the sheath includes reducing its thickness over all or part of its circumference and can, for example, be a recess. The switches are preferably positioned outside the straight section of the change in structure of the sheath.
According to another feature that, for example, enables a primer-tripping threshold to be introduced, the membrane switches are connected to a processor for processing electrical signals coming from the detector. The processor is able, in particular, to filter the targets and control the tripping of the primer.
According to one additional feature, the processor may include a counting module. According to another particular feature, the processor may be a microcontroller. According to another feature, the processor may be connected to the electrical power supply, to the detector, and to the primer-firing resistor.
According to an additional feature, the switch controlled by the processor is disposed between the processor and the primer-firing resistor. According to an additional feature, the timer is associated with the processor and/or the switch controlled by the processor.
The invention also relates to an explosive device of the type having an explosive charge, a primer, and a firing device for firing this explosive charge. The firing device may be a firing device according to one of the aforesaid features.